Smallhead barbel
(Luciobarbus microcephalus)

Luciobarbus microcephalus is a ray-finned fish species in the family Cyprinidae. It is here placed in Luciobarbus following the IUCN, but that genus is very closely related to the other typical barbels and perhaps better considered a mere subgenus of Barbus.

This small barbel is less than 26 cm (10 in) long when fully grown. It is endemic to the Iberian Peninsula, where it occurs in the middle and lower Guadiana River basin in both Portugal and Spain. A presumably introduced population is found in a small stretch of the Tagus. Its natural habitats are deep and slow rivers and reservoirs.

Its numbers are declining across its rather small range, and it is classified as Vulnerable by the IUCN. By 2020 its stocks will probably number less than half of what they were at the turn of the millennium. The main cause of its decline is unsustainable use of water resources, such as water pollution, extraction for agriculture and damming. Certain planned damming projects – e.g. one near Alquedi – are likely to severely impact the fish. Introduced exotic fishes and big predators pose an additional problem.